Polarized magnetic rings are commonly used in applications for determining the speed of rotating elements such as in the wheel bearings of motor vehicles. In these installations, the polarized magnetic ring is anchored on the rotating ring of the wheel hub bearing and a suitable sensor is located axially or radially opposite the magnetic ring to determine to rotational speed of the wheel and to transmit this information to appropriate processing systems that have various functions such as in AB SKF braking systems.
It has been found that in these installations there are certain disadvantages and drawbacks. For example, the polarized magnetic rings tend to attract metal particles normally present in the environment and this can cause problems with the detection of the signals and the proper functioning of the device in general. Furthermore, presently, the magnetic rings are usually mounted without additional constraints on the outer ring of the bearing. In these installations it has been found that vibrations, jolts and other sudden movements to which the bearing itself is subjected causes axial movement of the magnetic ring. This movement is undesirable since it adversely affects the accuracy of the sensing system.